Answer: Taxing agencies typically do not report directly the credit bureaus, so this lien must have turned up because of a public records search. This probably means that the tax lien was recorded in the county where the property that you sold was located.
You should be able to contact the county recorder's office or a title insurance company to get a copy of the lien. In some counties, the recorder's office may have an online search that would allow you track down the lien down yourself. Some, like the San Diego County Recorder's Office, allow you to order the documents online directly from them. Alternatively, most title companies will give you a copy for free as a customer courtesy.
The lien should have the name and address of the agency that levied the tax. Once you have this information, the taxing agency should be able to track down your file and tell you what you need to pay in order to settle this debt.
About the Author: Carl H. Starrett II has been a licensed attorney since 1993 and is a member in good standing with the California State Bar and the San Diego County Bar Association. Mr. Starrett practices in the areas of bankruptcy, business litigation, construction, corporate planning and debt collection.